Internal combustion engine exhaust muffler



Oct. 1, 1963 N. BEZEMES 3,105,570

INTERNAL COMBUSTION ENGINE Em-musT MUFFLER Filed April 17, 1962 2 Sheets-Sheet 1 INVENTOR.

N \CHOLAS BEzEMEs ATTORNEYS Oct. 1, 1963 N. BEZEMES 3,105,570

INTERNAL COMBUSTION ENGINE EXHAUST MUFFLER Filed April 17, 1962 2 Sheets-Sheet 2 INVENTOR.

N \CHOLA: Bezemes ATTQIZNEYS United States Patent Office 3,1055% Patented Oct. 1, 1963 3,105,570 INTERNAL COMBUSTION ENGINE EXHAUST MUFFLER Nicholas Bezemes, 15 Forest St., Peabody, Mass. Filed Apr. 17, 1962, Ser. No. 188,056 8 Claims. ((31. 181-56) This application is a continuation-in-part of my application Serial No. 87,802 for Intern-a1 Combustion Engine Exhaust Mufiler, filed February 8, 1961, now abandoned.

This invention relates to mufllers or silencers, and in particular to devices of this nature used in reducing the noise in the exhaust gases from internal combustion engines.

In the main, such devices in accepted usage are designed on the general principle of an enlarged expansion chamber in the exhaust line, equipped with baflles and ll abyrinths, and it is a general object of the present invention to provide a mufiler of simplified structures, as well as materially reduced weight and size. More particularly, it is an object to provide a muffler which requires merely an insert in an exhaust pipe of ordinary diameter.

Although perforate plug inserts for exhaust pipes have been proposed heretofore, they have been attended with serious shortcomings, especially in respect to excessive back pressures, undue heating, and power waste in general. It is therefore a further object to provide a plug insert mufiier which shall overcome the enumerated defects.

By actual experiment I have found that bored plugs, in plurality, and spaced relation, function as mufflers in a distinctly improved manner when constructed within certain ranges of tolerances as to plug length, in relation to the number of plugs, and the arrangement, and sizes of the bores, as described hereinafter.

For a detail description of a preferred embodiment of the invention, reference is made to the following specification, as illustrated in the drawing, in which:

FIGURE 1 is a perspective view of exhaust pipe, show ing a preferred modification, with three muffier plug inserts indicated in dotted lines within the pipe.

FIGURE 2 is an axial sectional view taken on the plane of the line 2-2 of FIGURE 1.

FIGURE 3 is a cross sectional view, taken on the line 33 of FIGURE 2.

FIGURE 4 is an end elevational view of a modified plug, showing an additional ring of bores.

FIGURE 5 is a bracketed view, in perspective, of a series of four plugs in the relative positions they would occupy in an exhaust pipe.

FIGURES 6 and 7 are views similar to FIGURE 5, showing arrangements, respectively, of a series of seven plugs, and a series of thirteen plugs.

Referring to the drawings by characters of reference, there is shown, in FIGURES l to 3, a metal exhaust pipe 10, of conventional construction and size, which when fitted with plug inserts according to the invention constitutes the entire mufiler unit. As shown in FIG- URES 1 to 3, the metallic plug inserts 12, three in number, and identical in size, shape and construction, are cylindrical in form, and provided with a series of longitudinally extending bores, including a large, central bore 14, and an outer, concentric ring of smaller bores 16, eight in number, spaced apart equi-angularly of the cylinder, and located midway of the distance between the central bore and the periphery of the plug.

The inserts 12 have a diameter sized to be received in the pipe .10 in a close fit, which reduces the effective opening to that aiforded by the bores 14 and 16, and the plug may be secured in place in any convenient manner. As shown, they are held by peripheral pressure on the 2 pipe 10, communicated by a split strap ring 18, with a fastening bolt 20 and nut 22. The plugs may also be held as by a shrink fit, or spot welding, and in another variation, may be rolled up in the tube 10 at the time of its manufacture.

The plugs 12 are located in spaced relation, along the pipe 11.0, defining a series of chambers 24, and the outermost plug is preferably located adjacent the exit end of the pipe.

The exhaust gases from an internal combustion engine, if uncontrolled, are emitted in pulses of high energy, and the physical conditions existing at the exit end of the pipe give rise to the objectionable series of reports similar to that of a fire arm. In all muffler devices the aim is to so tame these gases as to reduce them to a more even flow and at the same time dissipate as much energy as possible before exit, and one of the main problems is to accomplish these ends without undue lowering of efiiciency resulting from back pressures and heating effects. In the employment of the spaced plugs according to the present invention, the turbulent gases are constrained to a more even, or laminar, flow, by their conduction through the plug bores, and this process is rendered smooth and gradual by successive conduction through the tandem system of plugs, in cascade fashion, with the successive chambers 24 providing a buffer means for each stage of the energy-lowering process. Upon leaving the final plug the reduction is so thoroughly advanced that the gases emerge gently and with even flow.

The invention thus contemplates multiple, bored plugs in tandem, and through experiment I have discovered certain relationships in the system of plugs which provides optimum results, and which appear to lie within critical ranges of values. As a result, a preferred embodiment has been found as comprised in a system wherein the plugs may range in number from 2 to 13, with lengths substantially equal, and the spacing substantially equal to the lengths. The preferred plug diameter is 1 /8 inches, and on this scale the three plugs shown in FIGURE 2 are each 3 inches in length, and spaced 3 inches apart. The stepwise reduction of exhaust energy is enhanced and smoothed by increasing the number of plugs and spaces, without substantially varying the total plug length. Thus, in FIGURE 5, the system is shown as comprising four 2 inch plugs 26, spaced 2 inches apart, FIGURE 6 shows seven 1 inch plugs 28, spaced 1 inch apart, and FIGURE 7 shows thirteen /2 inch plugs 30, spaced /2 inch apart.

Also contributing to optimum results in the provision of a central bore larger than the outer ring of bores. While no theoretical basis for this eifect is presently apparent, it is probably somehow related to the resultant differential in flow characteristics between the axial stream and the outer streams, which brings about a temporary turbulence in the gases as they enter the expansion chambers, dissipating their energy in random, nonaxial movement, and this process, repeated stepwise in the system of plugs, results in a thorough taming of the gases before final emergence. In particular, I have found that with a plug of diameter 1 /8", as stated above, the central bore 14 preferably has a diameter of about Vs, and the preferred diameter for the bores in the outer ring is about %4". On this basis the total cross sectional area of the bores is about 8% of that of the plug, and a tolerance of A3" in the bore diameters would result in a variation of 2% in the 8% relationship, or a range of 6% to 10%.

If the plug diameter is increased as much as A2 inch above the preferred 1% inch value, a further, outer ring of inch bores may be added. These, preferably 16 in number, are indicated by the numeral 32 in FIG- URE 4.

As stated above, there appears to be an underlying relationship between the number of plugs and their length, and close examination shows this relationship as being expressable in the following formula:

where N is the number of plugs and L is their common i the existence of a critical range, as generally, defined by the formula, is supported.

Obviously the conditions defined by the formula are not precise, but subject to some latitude. For instance, While two plugs, of six-inch length could be employed, such a combination is not of a high order of preference, since the masses of the plugs in this range are likely to introduce objectionable heating elfects. Also, while little is to be gained by employing more than 13 plugs, some extension is nevertheless possible, and in this range, the difference in results between the use of 13 and 14 plugs, for instance, would not be great;

Notwithstanding certain limitations stated above, various modifications will become apparent, in the light of this disclosure, which will not constitute a departure from the basic concept of the invention, and the invention should not, therefore, be deemed as limited except insofar as shall appear from the spirit and scope of the appended claims.

I claim:

:1. A muffler comprising a tubular conduit of uniform bore, and a series of cylindrical plugs secured in said bore, in longitudinally spaced relation, said plugs being of substantially equal length, andseparated by a distance substantiallyequal to their common length, each plug having an axial bore, and a concentric ring of radially outer bores of smaller diameter than said axial bore, said plugs being of the order of 1 /8 inches in diametensaid axial bores being substantially Vs inch in diameter with a tolerance of about Ms inch, said outer bores being subinch in diameter, with a tolerance of about stantially having a length L substantially /8 inch, and said plugs according to the formula wherein Nais the number of plugs, in a range of values between 2 and 14 inclusive,

2. A device as in claim '1 wherein N=3.

3. A device as in claim 1 wherein N=4.

4., A device as in claim 1 wherein N :7.

5. A device as in claim 1 wherein N about 13.

v 6. A muffler comprisinga tubular conduit of uniform bore, and .a series of cylindrical plugs secured insaid bore, in'longitudinallyspaced relation, said plugs being substantially equal'in length, and separated by a distance substantially equal to their cornmonllength, each plug having an axial bore, and a plurality of radially outer bores of smallerdiameter' than said axialbore, said axial bores being substantially /8 inch in diameter, with a tolerance of about A; inch, said outer bores being substantially inch in diameter, with a tolerance of about A; inch, and said plugs having a length L substantially according to the formula:

' wherein N is-the number of plugs,'in a range of values I between 2 andl14, inclusive.

7. A device as in claim 6, said outer bores being eight in number, and arranged concentrically of the plug axis.

8. A device as in claim 6, said outerbores being arranged in a plurality of rings concentrically of the plug axis, and comprising an inner ring of eightbores, and an outer ring of sixteen bores.

References Cited in the file of this patent UNITED STATES PATENTS V 

1. A MUFFLER COMPRISING A TUBULAR CONDUIT OF UNIFORM BORE, AND A SERIES OF CYLINDRICAL PLUGS SECURED IN SAID BORE, IN LONGITUDINALLY SPACED RELATION, SAID PLUGS BEING OF SUBSTANTIALLY EQUAL LENGTH, AND SEPARATED BY A DISTANCE SUBSTANTIALLY EQUAL TO THEIR COMMON LENGTH, EACH PLUG HAVING AN AXIAL BORE, AND A CONCENTRIC RING OF RADIALLY OUTER BORES OF SMALLER DIAMETER THAN SAID AXIAL BORE SAID PLUGS BEING OF THE ORDER OF 1 5/8 INCHES IN DIAMETER, SAID AXIAL BORS BEING SUBSTANTIALLY 3/8 INCH IN DIAMETER WITH A TOLERANCE OF ABOUT 1/8 INCH, SAID OUTER BORES BEING SUBSTANTIALLY 17/64 INCH IN DIAMETER, WITH A TORLERANCE OF ABOUT 1/8 INCH, AND SAID PLUGS HAVING A LENGTH L SUBSTANTIALLY ACCORDING TO THE FORMULA 